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Malaria

Scientists search mosquito saliva for compounds that help transmit malaria

Research mosquitoes.Credit: NIAID

NIAID’s José Ribeiro, M.D., Ph.D., Vector Biology Section, Laboratory of Malaria and Vector Research, Division of Intramural Research studies the ongoing battle between humans and the more than 14,000 species of blood-sucking arthropods—mosquitoes, ticks, and other bugs—whose bites can spread potentially fatal diseases like malaria. His work focuses on the role of arthropod saliva in blocking the body's natural defenses and in aiding the transmission of disease-causing parasites.

Each arthropod species has a unique “salivary cocktail” that enables the bugs to drill through human skin without attracting attention, while maximizing the size and speed of its blood feast. Dr. Ribeiro and his team take saliva samples from mosquitoes and other arthropods and, with each sample, determine the "spitome," or the genetic sequences that encode all of the substances found in the saliva. Because most spitomes contain between 20 and more than 100 distinct chemical compounds, determining the function of each substance is painstaking work. For example, Anopheles gambiae, the primary mosquito species responsible for spreading malaria, has more than 70 compounds in its saliva.

To identify the function of each protein in the spitome, Dr. Ribeiro’s team makes recombinant proteins from the spitome genes and tests their effects on several different tissues and microorganisms. To identify the many novel proteins, Dr. Ribeiro counts on the help of staff scientists John Andersen, Ph.D., and Ivo Francischetti M.D., Ph.D., experts in structural and vascular biology.

Fellow NIAID researchers use the salivary genes identified by Dr. Ribeiro and his colleagues to develop and test experimental DNA vaccines that could one day be used to block the transmission of disease-causing parasites, like those that cause malaria, from mosquito to humans.